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Scientists have set a new record for the longest echo found in a man-made structure in a hidden network of oil storage tanks in Scotland.

Acoustic scientists found that a gun-shot fired in the Inchindown oil storage tanks, constructed during the Second World War as an underground fuel depot, resonates for a full 112 seconds.

The find smashes the previous record, also set in Scotland, of a 15-second echo of the sound of doors being slammed shut in the Hamilton Mausoleum. The new record has been certified by Guinness World Records.

Trevor Cox, Professor of Acoustic Engineering at the University of Salford, England made the recording after being tipped off about the complex's potential for acoustic resonance.

Inchindown was excavated out of solid rock between 1939 and 1941, the complex was embedded deep in the hillside as concerns mounted over increasing German military might and the threat of long-range bombers. The tanks were intended to provide a substantial supply of furnace fuel for the British fleet at nearby Invergordon, which was a key anchorage for the Royal Navy.

Professor Cox had to enter by descending through one of the 18-inch oil pipes as the complex features no doors. Each tank was designed to hold 25.5 million litres of fuel and is roughly twice the length of a football field.

A gun containing blank cartridges was fired in the tank and Cox was astonished by the recording his microphones picked up.

He says, "It was like going underground into a Bond villain's lair. But never before had I heard such a rush of echoes and reverberation. I just started off playing around, whooping and hollering. The sound just goes on and on and on. Then when we fired the pistol my initial reaction was disbelief; the reverberation times were just too long. I knew immediately we had a new world record."